Introduction
A hybrid solar-mains system combines grid power, solar generation and battery storage. The operating priority and transfer behaviour depend on the selected equipment and control design. For critical intersections, verify the required backup duration, source-failure response and signal operation during transfer. This guide covers these design considerations.
Why Hybrid?
Three reasons to choose hybrid over pure solar or pure mains:
- Grid outage resilience: during a grid outage, verify battery support for the required duration using the actual load, battery condition and operating environment.
- Lower operating cost: allocate solar and grid energy from the actual generation, load profile and source-control strategy; do not assume a fixed daytime share.
- Lower carbon footprint: assess hybrid-system reliability and renewable-energy contribution from the actual architecture, site resource, load and control strategy. Do not assume grid-equivalent reliability or a universal 60-70% renewable share without project-specific evidence.
Compare hybrid, mains-only and solar-only systems using quotations for the same load, autonomy and service requirements. Do not assume a fixed percentage premium. At critical sites such as major roads, hospitals or fire-station approaches, evaluate supply resilience, failure response and lifecycle cost before choosing a hybrid arrangement.
System Components
A hybrid system has:
- Mains input (110V or 220V AC) with surge protection
- Solar panel and MPPT charge controller
- Size the battery bank for the required night operation and backup duration
- Inverter/charger that combines mains and battery
- Controller and signal heads: confirm compatibility with the selected supply architecture and changeover arrangement. Equipment used in a pure-solar or mains installation is not automatically suitable for a hybrid system.
The charger and transfer equipment manage source selection in a hybrid system. Confirm the selected equipment’s transfer time, switching behaviour, load compatibility and fault response with GAOQIAO. Verify the complete signal system during transfer rather than assuming uninterrupted operation from a component description.
Sizing the Battery
For a hybrid system, calculate battery demand from the approved source-priority and outage scenarios, including daytime operation where required. Allocate the load by operating mode and verify reserve and recharge requirements:
- Daytime battery demand: calculate from actual solar generation, load and source-control behaviour.
- Night (12 hours, battery): full signal load (e.g., 80 W average for a 4-leg intersection)
- Grid outage: include all loads that must continue operating during the required backup period, including daytime loads where applicable.
Battery sizing must cover the energy demand during the required autonomy period, not only night-time operation. Use the full load profile, allowable depth of discharge, conversion losses, temperature and ageing margins, and verify recharge performance. Convert required usable energy to nominal capacity at the selected battery voltage.
Size the battery from the actual energy balance, required backup duration and recharge conditions; do not assume half the capacity of a solar-only system.
Featured Products
GAOQIAO supplies hybrid solar-mains controllers and hybrid signal heads. See the solar vs mains comparison.
Conclusion
A hybrid power arrangement may be considered where the project requires operation during grid outages. Define the load profile, required autonomy, grid conditions, charging strategy and recovery requirements. Ask GAOQIAO to confirm the available equipment and compatible battery options for the project. Do not assume a standard hybrid package or that hybrid power is always the preferred solution.
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Frequently Asked Questions
What happens if both grid and battery fail?
Loss of power may leave a signal dark unless a suitable backup supply is operating. Follow the authority’s approved incident and temporary traffic-control procedure, notify the responsible operator and arrange qualified maintenance. Do not improvise signs or signal states at an active intersection.
How fast does the transfer switch operate?
Confirm the selected hybrid charger’s transfer performance and compatibility with the actual controller and load. Test signal behaviour during source changes and faults; a component switching-time figure alone does not establish uninterrupted operation or universal controller compatibility.
Can I retrofit a hybrid system to an existing mains-powered signal?
A solar retrofit requires an engineered assessment of the panel, charger, battery, changeover arrangement, existing equipment and protection. Confirm compatibility and any available retrofit supply with GAOQIAO before modifying the system.
Relevant GAOQIAO products
These public GAOQIAO catalogue pages are related to the guide. Open them for the representative description, then confirm the latest drawing and configuration before ordering.
- Traffic signal controllersWired and solar controllers with 6, 22, 44 and 56 output options.
- LED traffic signal heads200mm, 300mm and 400mm signal heads; confirm the selected model and applicable project requirements.
- Signal polesVertical, signal arm and double-arm poles; confirm suitability for the approved site design.
- Spare parts and accessoriesSpare LED modules, lenses, visors, surge arrestors and anchor bolts.
Related buyer resources
- Traffic Signal Controller Cabinet Guide
- Traffic Light Wiring Diagram Guide
- Traffic Light IP Ratings Guide
- Traffic Signal Head Specification Guide
- Solar Traffic Signal Site Survey
- Contact GAOQIAO
Request a quotation for hybrid solar and mains traffic signals
Related guides: solar power
Continue with these related resources for your traffic signal project.